Does replugging a Thunderbolt display necessitate a system restart?
Is there any danger in hot-plugging and un-plugging an external (Apple) Thunderbolt monitor (from USB-C)?
It is absolutely normal to hot-plug/unplug an external display connected over Thunderbolt or USB-C port of your Mac.
It is not required to shutdown your Mac just to plug/unplug an external display.
Unless the plugged device shows me the eject button in front of its icon, I don't wait until the system gets shut down to remove the external device that I plugged in. Please check if there is a manual to the monitor that have for additional details related to power supply.